Cyphomyrmex bruchi Santschi

Kempf, W. W., 1964, A revision of the Neotropical fungus-growing ants of the genus Cyphomyrmex Mayr. Part I. Group of strigatus Mayr (Hym., Formicidae)., Studia Entomologica (N. S.) 7, pp. 1-44 : 34-36

11. Cyphomyrmex bruchi Santschi

(Figs. 10, 21, 32, 53)

Cyphomyrmex bruchi Santschi , 1917: 282 (Worker; Argentina: La Plata). - Santschi, 1931: 281, figs. 5, 6 (Worker; Argentina: La Plata, Buenos Aires). - Weber. 1940: 408 (Key). - Kusiezov, 1949: 436, 438. - Kusnezov, 1957: 10-11 (Key).

Types. - 3 workers, collected by C. Bruch at La Plata, Buenos Aires Province, Argentina, n. 631; 2 specimens, lectotype (Coll. Santschi, NHMB) and paratype (WWK) seen.

Worker (lectotype) - Total length 3.0 mm; head length 0.72 mm; head width 0.72 mm; maximum diameter of eyes 0.11 mm; scape length 0.56 mm; thorax length 0.93 mm; hind femir length 0.67 mm. Brown; head fuscous reddish brown. Opaque; finely reticulate-punctate; dorsum of head between frontal carinae and less conspicuously dorsum of gaster rather finely and somewhat irregularly reticulate-rugose. Tergum I of gaster without evident small, piligerous tubercles. The whole insect covered with fine, appressed, scattered and glittering short hairs. Tip of gaster (terga and sterna II-IV) with short and erect hairs.

Head as shown in Fig. 10; as broad as long. Mandibles finely punctate and vestigially striolate; chewing border with more than 7 vestigial to indistinct teeth (sign of wear?); sides sharply carinate at base; apical tooth prominent. Anterior clypeal border shallowly emarginate in middle, laterally with a small tooth. Frontal area distinct. Frontal carinae anteriorly expanded into prominent subcircular lobes, posteriorly greatly removed from each other and slightly diverging and sinuous, confluent with preocular carina on occipital corner. Vertex without paired carinules. Occiput broadly and shallowly excised between prominent occipital corner (Fig. 53), with another deeper and narrower excision in the middle. Supraocular tumulus very broad, low and blunt. Scapes in repose not surpassing the occipital corners. Funicular segments II-VI1F about as broad as long.

Thorax as shown in Fig. 21. Pronotum with a pair of low and stout lateral tubercles, midpronotal tubercle practically absent; anteroinferior corner angulate and subdentate. Mesonotum without marked anterior tubercles, posterior tubercles indicated by the sharply marginate, in profile weakly raised, posterior corners. Mesoepinotal groove in the middle very shallow, laterally more deeply impressed. Sides of basal face of epinotum bluntly marginate. Epinotal teeth short and pointed. Dorsum of thorax between pronotal tubercles and epinotal spines flattened to slightly excavated on posterior half of basal face of epinotum. Hind femora ventrally dilated at basal third, the posterior border bearing there a prominent foliaceous flange.

Pedicel as shown in Figs. 21 and 32. Petiolar node subtrapezoidal in dorsal aspect, broader in front than in back, anterior corners rounded, posterior border dorsally with a distinct, obliquely raised, short transverse laminule, flanked by a short, longitudinal carinule. Anterior face distinct from dorsum. Postpetiole a little more than twice as broad as long (31: 15), with laterally prominent rounded lobes. Tergal portions of both pedicelar segments ventro-laterally excavate with foliaceous margins, that are not appressed on sternites. Postpetiole posteriorly with a median and two lateral impressions. First gastric tergite antero-laterally submarginate.

The present species is only known from the few type specimens.

Discussion. - C. bruchi , although the mandibles bear in the types scarcely distinguishable teeth, except the apical one, belongs doubtless to the strigatus-group, as shown by the arrangement of the frontal carinae and preocular carinae. It is misplaced both in Weber's (1940) and especially in Kusnezov's (1949 and 1957) keys. According to the latter, it would fall into the rimosus-group.

The closest relatives are found in the difficult olitor-subgroup. Following are the most outstanding differences from the better known species of this assembly.

It differs from lectus Forel in larger size; in the shape of the frontal lobes, which are less expanded laterad and distinctly subcircular in outline; in the indistinct dentition of the mandibles; in the lack of paired carinae on vertex, in the antero-inferior tooth of pronotum which is not greatly produced; in the ill-defined anterior mesonotal tubercles; in the feebly impressed mesoepinotal groove; in the long basal face of epinotum, which is about as long the declivous face; in the extremely broad postpetiole of different shape.

C. daguerrei Santschi is even more remote, from which bruchi workers may be distinguished at once by the less produced clypeus, by the better developed frontal lobes, the smoother head sculpture, the lack of vertical carinae, the length of the antennal scapes, which do not surpass in repose the occipital lobe, by the sharply carinate posterior borders of the antennal scrobe, by the absence of a midpronotal tubercle and the weak lateral ones, by the absence of anterior and the ill-developed posterior mesonotal tubercles, by the shallowly impressed mesoepinotal groove, by the ventrally angulate and carinate hind femora, by the extremely transverse postpetiole, by the lack of piligerous tubercles on first gastric tergite.

On account of the broadly transverse postpetiole it resembles somewhat quebradae , which I have synonymised with olitor on a preceding page. The shape of the head in full-face view (especially the broadly expanded frontal lobes and widely separated frontal carinae, the absence of carinules on vertex, and the vestigially dentate mandibles), the dorsally flattened thorax with obsolete antero-lateral mesonotal tubercles, the broadly expanded petiole, with the lateral lobes deeply excavate from underneath and foliaceous, the absence of piligerous tubercles on gastric tergum I, separate bruchi from the higly variable olitor .